| The dispersion data and dispersion curves can be used to measure the transverse wave velocity of the formation,invert the maximum and minimum horizontal ground stress,and analyze the lateral anisotropy,etc.The dispersion curves of flexural waves under different conditions are very different.By studying the influencing factors of dipole flexural wave dispersion curves,the accuracy of dipole dispersion correction results in soft formation can be improved,which is important for the later analysis and interpretation work using acoustic wave transverse velocity.In this thesis,the influence of the parameters on the dispersion curves under different source conditions,different formation conditions,different borehole conditions and different logging instrument conditions is studied by using the weighted spectral semblance method,and the accuracy of the theoretical analysis is proved by the measured data.Different parameters have different effects on the dispersion curve of flexural wave.The source center frequency and the source distance of the dipole sound source have almost no effect on the dispersion curve of the flexural wave.When the dipole sound source is eccentric,the eccentric azimuth and offset distance of dipole source have certain influence on the dispersion curve of flexural wave.The formation compressional wave velocity has little effect on the dispersion of flexural waves.The shear wave velocity of the formation and the degree of formation hardness have a greater effect on the dispersion,and they have similar effects on the dispersion of the flexural wave.The influence of fluid compressional wave velocity on dispersion is very small.The ratio of formation density to fluid density has a greater influence on dispersion,and the smaller the density ratio,the greater the influence.Well diameter has a great influence on the dispersion curve of flexural waves.Logging tool also affect the dispersion curve of flexural waves,and the larger the radius of the logging tool,the greater the influence on dispersion. |
